Multilumen catheters are used to simultaneously infuse a plurality of fluids into a patient, the separate lumens of the catheters preventing fluids from mixing during the infusion process and before the fluids enter the patient's body. Preventing fluid mixing is particularly important where the simultaneously infused fluids are chemically incompatible.
Multilumen catheters are also useful for simultaneous infusion of fluids and withdrawal of samples of the patient's body fluids, thus avoiding the need for insertion of multiple separate catheters into the patient.